The disclosure relates generally to turbo-machinery, and more particularly, to a rotor turning system and method for turning a rotor, for example, when there is no turning gear coupled to the rotor.
Turbomachines are used to generate power, for example, in the form of electricity when coupled to an electric generator. Turbomachines may take a variety of forms such as a gas turbine, jet engine or steam turbine. Each form of turbomachine may include one or more turbine components that are driven by a working fluid such as combustion gases or steam to turn a rotor coupled to the turbine component. In many cases, the rotor is coupled to numerous turbine components, and extends to a generator for generating electricity. The generator may also provide turning gear for turning the rotor during startup of the particular turbine system.
During maintenance of a turbomachine, the rotor is uncoupled from various components to allow access to the components and the rotor. For example, in a gas turbine system, the gas turbine component is uncoupled from the generator during maintenance. In this setting, there is no generator turning gear to turn the rotor even though some turning of the rotor may be necessary during maintenance. The torque necessary to turn the rotor typically must be sufficient to not just turn the rotor but also the turbine component, and possibly the generator rotor, that may remain coupled to the rotor (e.g., by a load coupling shaft). One approach to provide turning includes employing a pinion gear integrally built into or added to an end of a rotor, and a mating geared drive to turn the rotor using the pinion gear. This arrangement requires the rotor to be made with the pinion gear or the pinion gear must be permanently affixed to the end of the rotor. In most cases however the rotor is not manufactured or readily capable of having the pinion gear mounted to an end thereof. In most cases however the rotor only has a smooth exterior surface, which may be presented on a flange that extends radially from a remainder of the rotor. As a result, during maintenance, workers typically have to employ chain falls, ‘come-alongs’ or cranes to assist in turning the rotor. This approach to turning a rotor is not a controlled method and may inhibit providing quality maintenance.